The invention is based on a fuel injection system for motor vehicles as defined hereinafter. U.S. Pat. No. 4,777,921 discloses a fuel injection system of this kind in which a high-pressure fuel pump supplies fuel from a low pressure chamber into a high-pressure accumulation chamber, which communicates via high-pressure lines with the individual injection valves protruding into the combustion chamber of the engine to be supplied; this common pressure storage system (common rail) is maintained at a certain pressure by a pressure control device at the high-pressure pump so that regardless of the engine speed, the injection pressure at the injection valves can be determined over the entire operating performance graph of the engine to be supplied. To control the injection times and injection quantities at the injection valve, an electrically controlled control valve is inserted into the high-pressure lines at the injection valve; by its opening and closing, this control valve controls the high-pressure fuel injection at the injection valve.
However, the known fuel injection system has the disadvantage that a rapid pressure drop in the pressure storage system is not possible or is not possible to a sufficient extent if the engine speed is constantly changing or if the engine is stopped. Furthermore, the known fuel injection system has no effective safety device to protect against a pressure increase over an admissible maximal pressure or against an uncontrolled escape of fuel from the pressure storage system, e.g. as a result of a breach of a high-pressure line, so that it cannot satisfy the current requirements with regard to functional safety and emergency operation properties.